Yarn tension device for knitting machines



y 1940- J. E. GARRETT 2,209,398

YAf m TENSION DEVICE FOR KNITTING MACHINES Filed May 12, 1938 7'5 3., menial; 2o Joszm EARNEST GARRETT Patented July 30, 1940 UNITED s'rA'ri-zs PATENT OFFICE YARN TENSION DEVICE FOR KNITTING MACHINES Application May 12, 1938, Serial No. 207,476

1 Claim.

This invention relates to improvements in knitting machines and more particularly to an improved yarn tensioning mechanism for insuring even tension of the yarn as it is laid across the 6 noses of the sinkers and dividers of the knitting machines.

As is well appreciated in the knitting art, particularly in the full-fashioned hosiery art, cor rect yarn tension is an important factor in the 10 production of loops of uniform size and shape and in the formation of a perfect selvedge along the longitudinal edge of the knitted stocking blank. It frequently occurs that during the process of knitting the stocking fabric, especialiy when the yarn carrier rod strikes its end stop at the completion of its stroke in a given direction, the tension of the yarn is sodisturbed as to result in the production of an irregularly formed and unsightly selvedge. Also, during the narrowing process, unless the tension on the yarn is properly maintained, the loops may be dropped from the narrowing points with the result that the knitted fabric is spoiled.

In addition to the foregoing, difllculties have been encountered due to the natural tendency of the yarn, particularly when composed of silk, to curl and twist to form what. are known as snarls" in the yarn, which interfere with the proper knitting operations and render the fabric 9 so unsightly that it must be rejected as irregular.

It is among the objects of the present invention to provide a yarn tensioning mechanism which obviates the aforementioned difliculties, which insures the constant maintenance upon the 35 yarn of the requisite tension, which automatically Z takes up the slack in the yarn whenever the knit-a ting operation is interrupted, as when the yarn carriers reverse in their directions of movement, and which maintains sufficient tension upon the 40 yarn during the narrowing process as to prevent the loops being displaced from the narrowing points.

A further object of the invention is to provide a yarn tensioning device which not only insures 45 the constant maintenance of requisite tension on the yarn to thereby produce loops identical in shape and size, but which also serves to smooth out of the yarn all such curls and twists which ordinarily result in the formation of snarls in the 50 knitted fabric.

Other objects of the invention will appear more fully hereinafter.

The invention consists substantially in the combination, construction, location and relative ar- 56 rangement of parts, all as will appear more fully hereinafter, as shown in the drawing, and as finally pointed out in the appended claim.

In the accompanying drawing:

Figure 1 is a side elevational view of a portion of a knitting machine equipped with the yarn 5 tensioning device constructed in accordance with and embodying the principles of the present in-' vention;

Figure 2 is a front elevational view thereof;

Figure 3 is a side elevational view of the yarn 10 tensioning device per se, showing the position assumed by itwhen the knitting operation is interrupted;

Figure 4 is a similar view showing the position assumed by the tensioning device during the knitl5 ting operation; and

Figure '5 is a front elevational view of a portion of the device shown in Figure 4.

Referring now more particularly to the drawing, it will be observed that the yarn tensioning so mechanism of the present invention, designated generally by the reference numeral I 0 in Figure 1,

is shown incorporated in a knitting machine ll, only so much of the latter being illustrated as is deemed necessary for a clear understanding of 25 the construction and operation of the yarn tensioning mechanism. It will be understood, of course, that the latter mechanism may be incorporated in any of the conventional knitting machines, it being particularly adapted for installation in and as part of the flat-bed fullfashioned type of knitting machines such as are conventionally employed in the production of full-fashioned hosiery. These knitting machines are usually provided with yarn-tensioning devices suitably located between the source of yarn supply and the knitting head of the machine and generally embody an intermittently operated yarn tension device, commonly known as a snapper,- and operating cams for automatically actuating the snappers to provide for proper tensioning of the yarn while the yarn carriers are being moved across the knitting-field, particularly during the narrowing operations. The snappers heretofore employed as yarn tensioners have been in the form of cast metal fixed elements fitted with porcelain eyes and having operatively associated therewith leaf springs-which press upon the yarn as the latter passes through the porcelain eyes to produce the required yarn tension. tion, these conventional yarn tensioning devices or snappers have had operatively associated therewith a' ring tension device generally embodying a ring'loosely fitted upon a vertically disposed rod or holder therefor in such manner that 55 In addiwhen the yarn was projected through the ring the latter was free to drop by gravity along its supporting rod to take up the slack between the source of yarn supply and the snapper.

As will presently appear, the yarn tensioning mechanism of the present invention eliminates these snappers, their operating cams and the ring tension assembly operatively associated therewith and in lieu thereof employs an exceedingly simple and inexpensive arrangement of elements which are automatically self-operative to insure the maintenance of a constant tension upon the yarn at the same time that they operate automatically to take up the slack: in the yarn between the point where the yarn enters the knitting machine in advance of the tensioning device and the point where it enters the knitting field to be formed into loops.

As appears most clearly in Figures 3 to 5, inclusive, the yarn tensioning device of the present invention includes a pair of helical wire coils H and I2 each formed with the convolutions thereof spaced well apart. The inner ends l3 and I4 of these helical coils are secured to a common dinal axis," of the stationary upper coil ll.

between it and the head IQ of the pin. The rear extremity l3 of the helical coil l I is clamped between said nut l8 and a second locking nut 20 to immovably secure the helical coil II in the position shown, while the rear extremity of the coil 12 is loosely mounted upon the pin l5, as at 2|, in such manner as to permit the coil l2 to move freely about said pin l5 as an axis. In

order to limit the downward movement of the .coil l2, the rear or inner extremity thereof is provided with. a free extension 22a which is adapted to abut against and engage the base plate of the bracket l6 (see Figure 3).

The coil I2 is thus relatively movable with respect to the coil II. In addition, these coils are so mounted relatively to each other that the longitudinal axes thereof lie in a common vertical plane, the convolutions of the coils being relatively so arranged that when the lower coil 12 is moved upwardly from the position shown in Figure 3 into that shown in Figure 4 the convolutions of one coil respectively nest within the spaces between the proximate convolutions of the other coil. In order to eliminate any possibility of interference between convolutions of the juxtaposed coils such as would prevent free movement of the coil l2 relatively to the coil II, the

convolutions of the two coils are spirally wound in opposite directions. Secured in the vertically disposed base plates of the bracket I6 is a porcelain eye 22 the opening through which is in substantial coaxial alignment with the longitu- The upper extremity of the bracket is reversely bent, as at .23Tto'provide a hook-like support by which @the bracket It may be suspended from the upper longitudinally extending bar24; of the knitting machine frame.

It will be understood, of course, that a tensioning unit such as is shown in Figures 3 and 4 is employed in conjunction with each yarn carrier of the knitting machine, the yarn being delivered from its source of supply to and through the ten sloning device and thence to the yarn carrier. As appears in Figure 1, the yarn is delivered from its source of supply, namely, the bobbin 2! disposed within a conventional humidifier 2| located to the rear of the knitting machine to and through the usual moistening trough 21, thence through the coils II and 12 of the tcnsioning device (see Figure 4) and thence over a suitable yarn guidingbracket 28 from which the yarn is finally delivered to the knitting head of the machine. The yarn guiding bracket 28, one of which is provided for each coiled wire tensioning device, is mounted upon a fixed element of the knitting machine frame such as the bar 29, the bracket 28 being adapted to be fixed in angularly adjusted position upon said bar 29 by means of a set screw 30. This bracket 28 is provided with an upstanding lug 3| which is fitted with a porcelain eye 32 while its outer or forward free extremity is fitted with a porcelain shoe 33. The yarn, as it emerges from the moistening trough 21, passes through a porcelain eye 34 and thence through the porcelain eye 22 of the tensioning device from whence it is threaded through the bores of the coiled wire elements II and I2. Upon emergence from these latter elements, the yarn is fed through the porcelain eye 32 and thence over the porcelain shoe 33 of the bracket 28 from whence it is delivered to the knitting head of the machine. i

In threading the yarn through the coiled wire elements II and I2, the coil I2 is lifted upwardly with respect to the coil H so that the convolutions.of one coil overlap or nest with the convolutions of the other with the resultthat the bores of the two coils are brought into substantial registry one with the other. The yarn may then be threaded commonly through the registering bores of the coils H and I2. Upon release of the coil [2 so that it drops into the position shown in Figure 3, the yarn will be found to be interlaced between the proximate convolutions of the separated coils l l and I2. It will be apparent that when the coil 12 drops into its lowered position shown in Figure 3 due to its own weight, any slack in the yarn between the delivery end '35 of the coil l2 and the knitting head of the machine is immediately taken up. Of course, during the operation of the knitting machine and while the yarn carrier is moving in either direction to lay sufficient pull on the coil member l2 to lift it into the position shown in Figure 4. However, immediately that the knitting operation is interrupted sufficiently for the yarn to become slack, the lower coiled member I2 drops of its own weight to the extent permitted by the slack in the yarnwith the result that all such slack is substantially eliminated. Upon resumption of the knitting operation so that the yarn is again drawn positively across the knitting elements of the machine, the pull of the yarn through the coils II and I2 tends to straighten it out and in so doing causes the lower coil l2 to lift into partial registry with the stationary upper coil II as shown in Figure 4.

It will be noted that at all times during the knitting operation, the weight of the lower coil I2 is suspended from the yarn at the points 36,as a result of which the yarn is caused to bear more or less firmly, at the points 31, against the bottom edges of the convolutions of the-upper coil ll. Accordingly. successive portions of the yarn. as

they traverse the coils II and II, are constantly subjected to positive tensions which tend to straighten and smooth the yarn tree of all such curls and twists as might result in the formation of snarls during the knitting operation. Also, during those intervals when the knitting operation is interrupted for any cause. the weight of the lower coil element l2 suspended from the points 38 of the yarn is suflicient to draw the yarn into the sinuous shape shown in Figure 3, the slack in the yarn in advance ofthe delivery end 35 of the coil I! being absorbed by the increased length of the yarn embraced within and between the coils H and [2.

It will be lmderstood, of course, that the invention is susceptible of various changes and modi flcations without departing from the general principles or real spirit thereof, and accordingly it is intended to define the invention broadly, as well as specifically, as indicated by the appended claim.

What is claimed as new and useful is:

A yarn tensioning device comprising, in combination, a relatively fixed open-coiled member, a second open-coiled member operatively associated with said fixed member and adaptedto shiit in the plane of the axis of said fixed member. the inner ends oi said members being mounted upon a common support while the outer ends volutions to be .Ireely brought into 'or out of inter- 20 jacent relation as the pull on the yarn delivered through said members is increased or decreased. 

